Re: A simpl(e)ification
- To: mathgroup at smc.vnet.net
- Subject: [mg105794] Re: A simpl(e)ification
- From: Peter Breitfeld <phbrf at t-online.de>
- Date: Sat, 19 Dec 2009 06:26:21 -0500 (EST)
- References: <hgd7qr$bkk$1@smc.vnet.net>
Simplify doesn't like the b in the denominator (I don't know why), but
Simplify[Im[Exp[-2 I a] 1/b], {a, b} \[Element] Reals && b != 0]
will work. But usually it's easier to use ComplexExpand instead of
Simplify, which treats all variables as Reals.
Pianiel wrote:
> Dear All,
>
> With Mathematica 7.0.1, the following expression;
>
> Simplify[ Im[E^(-2 I a) b], Assumptions -> Element[a, Reals] &&
> Element[b, Reals]]
>
> gives
>
> -b Sin[2 a]
>
> But:
>
> Simplify[ Im[E^(-2 I a) 1/b], Assumptions -> Element[a, Reals] &&
> Element[b, Reals]]
>
> gives
>
> Im[E^(-2 I a)/b]
>
> So we see that the Im[] is not simplified. Why?
>
> Any idea how to help mathematica to handle the simplification shown in
> the second example. It seems to be so similar to the first kind...
>
> Thanks in advance
>
> Pianiel
>
--
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de